3D DEM simulation of hard rock fracture in deep tunnel excavation induced by changes in principal stress magnitude and orientation  

作　　者：Weiqi Wang Xia-Ting Feng Qihu Wang Rui Kong Chengxiang Yang 

机构地区：[1]Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines,Northeastern University,Shenyang,110819,China [2]Hubei Key Laboratory for Efficient Utilization and Agglomeration of Metallurgic Mineral Resources,Wuhan,430081,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2024年第10期3870-3884,共15页岩石力学与岩土工程学报（英文）

基　　金：the financial support from the National Natural Science Foundation of China(Grant No.51839003);Liaoning Revitalization Talents Program(Grant No.XLYCYSZX 1902);Hubei Key Laboratory for Efficient Utilization and Agglomeration of Metallurgic Mineral Resources(Grant No.2023zy002).

摘　　要：To achieve the loading of the stress path of hard rock,the spherical discrete element model(DEM)and the new flexible membrane technology were utilized to realize the transient loading of three principal stresses with arbitrary magnitudes and orientations.Furthermore,based on the deep tunnel of China Jinping Underground Laboratory II(CJPL-II),the deformation and fracture evolution characteristics of deep hard rock induced by excavation stress path were analyzed,and the mechanisms of transient loading-unloading and stress rotation-induced fractures were revealed from a mesoscopic perspective.The results indicated that the stressestrain curve exhibits different trends and degrees of sudden changes when subjected to transient changes in principal stress,accompanied by sudden changes in strain rate.Stress rotation induces spatially directional deformation,resulting in fractures of different degrees and orientations,and increasing the degree of deformation anisotropy.The correlation between the degree of induced fracture and the unloading magnitude of minimum principal stress,as well as its initial level is significant and positive.The process of mechanical response during transient unloading exhibits clear nonlinearity and directivity.After transient unloading,both the minimum principal stress and minimum principal strain rate decrease sharply and then tend to stabilize.This occurs from the edge to the interior and from the direction of the minimum principal stress to the direction of the maximum principal stress on theε1-ε3 plane.Transient unloading will induce a tensile stress wave.The ability to induce fractures due to changes in principal stress magnitude,orientation and rotation paths gradually increases.The analysis indicates a positive correlation between the abrupt change amplitude of strain rate and the maximum unloading magnitude,which is determined by the magnitude and rotation of principal stress.A high tensile strain rate is more likely to induce fractures under low minimum principal stress.

关 键 词：Deep hard rock tunnel Three-dimensional(3D)discrete element model(DEM) Magnitude and orientation of principal stress Transient unloading Fracture mechanism 

分 类 号：TU45[建筑科学—岩土工程]